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Nuclear Chemistry
1
Facts About the Nucleus
Very small volume compared to
volume of atom
Essentially entire mass of atom
Very dense
Facts About the Nucleus
(continued)
Composed of protons and
neutrons that are tightly held
together
Nucleons
Every atom of an element has
the same number of protons
Atomic Number (Z)
Facts About the Nucleus
(continued)
Isotopes are atoms of the same
elements that have different
masses
Different numbers of neutrons
Mass Number (A)
= number of protons + neutrons
Facts About the Nucleus
(continued)
The nucleus of a specific isotope
is called a nuclide
less than 10% of the known
nuclides are nonradioactive,
most are radioactive
(radionuclides)
Nuclides
Each nuclide is
identified by a
symbol where:
A
X = element symbol
A = mass number Z X
Z = atomic number
Nuclear Reactions
with respect to other changes
Energy drives all reactions, physical, chemical, biological, and nuclear.
Physical reactions change states of material among solids, liquids,
gases, solutions. Molecules of substances remain the same.
Chemical reactions change the molecules of substances, but identities
of elements remain the same.
Biological reactions are combinations of chemical and physical
reactions.
Nuclear reactions change the atomic nuclei and thus the identities of
nuclides. They are accomplished by bombardment using subatomic
particles or photons.
Nuclear Reactions
changing the hearts of atoms
Nuclear reactions, usually induced by subatomic particles a, change
the energy states or number of nucleons of nuclides.
After bombarded by a, b
A (a,b) B
the nuclide A emits a
subatomic particle b, a
and changes into B.
a+A B+b
A B
or written as A (a,b) B
Nuclear Reactions
Radioactive decay – a process by which the nucleus
of a nuclide emits radioactive particles
Artificial Nuclear Transformation – the changing of
one element into another by bombarding it with a
nuclide
Nuclear Fission – the process of using a neutron to
split a heavy nucleus into two smaller nuclei
Nuclear Fusion – the process of combining two light
nuclei
Subatomic Particles for and from
Nuclear Reactions
Subatomic particles used to bombard or emitted in nuclear reactions:
gamma ray (photon) deuterons
0γ 2
1 D
electrons alpha particles
0 4
1 e He
2
protons beta particles
1
1 p 1
1 H
0
1
neutrons atomic nuclei
1 A
0 n Z X
Nuclear equations rules
Sum of reactant mass numbers = sum of
product mass numbers
Sum of reactant atomic numbers = sum
of product atomic numbers
“emitted” particles are on product side
“bombarding” or “captured” particles are
on reactant side
Radioactive Decay
Radioactive nuclei spontaneously
decompose into smaller nuclei
We say that radioactive nuclei are
unstable
Decomposing involves the nuclide
emitting a particle and/or energy
Radiation
Radiation comes from the nucleus of an
atom.
Unstable nucleus emits a particle or energy
alpha
beta
gamma
4
alpha decay 2 He
an particle contains 2 protons and
2 neutrons
helium nucleus
Alpha Decay
A Z A–4
P DZ–2
4He2
Alpha decay (continued)
222
88 Ra He
4
2
218
86 Rn
Beta decay
a particle is like an electron
moving much faster
found in the nucleus
in beta decay a neutron changes into
a proton
Beta decay (continued)
234
90 Th 0
1 e 234
91 Pa
gamma emission
Gamma () rays are high energy
photons
Gamma emission occurs when
the nucleus rearranges
No loss of particles from the
nucleus
gamma emission
(continued)
No change in the composition of the
nucleus
Same atomic number and mass
number
Generally occurs whenever the
nucleus undergoes some other type
of decay
positron emission
positron has a charge of +1 and
negligible mass
anti-electron
positrons appear to result from a
proton changing into a neutron
Positron emission
(continued)
22
11 Na e Ne
0
1
22
10
electron capture
occurs when an inner orbital
electron is pulled into the nucleus
no particle emission, but atom
changes
–same result as positron
emission
Electron capture
(continued)
200
80
Hg 1e
0 200
79
Au
Artificial Nuclear
Transformation
Nuclear transformation involves
changing one element into another
by bombarding it with small nuclei,
protons or neutrons
reaction done in a particle
accelerator
Artificial Nuclear
Transformation (continued)
man-made transuranium
elements
238
92 U C4 n
12
6
1
0
246
98 Cf
Other Nuclear Changes
a few nuclei are so unstable,
that if their nucleus is hit just
right by a neutron, the large
nucleus splits into two smaller
nuclei - this is called fission
Fission
U n Ba Kr 3 n
235
92
1
0
142
56
91
36
1
0
Other Nuclear Changes
(continued)
small nuclei can be accelerated
to such a degree that they
overcome their charge repulsion
and are smashed together to
make a larger nucleus - this is
called fusion
Fusion
2
1 H H He
2
1
4
2
Other Nuclear Changes
(continued)
both fission and fusion
release enormous amounts of
energy
Learning Check NR1
Write the nuclear equation for the beta
emitter Co-60.
Solution NR1
Write the nuclear equation for the
Beta emitter Co-60.
60Co 60Ni + 0e
27 28 -1
Learning Check NR2
What radioactive isotope is produced
in the following bombardment of
boron?
10B + 4He ? + 1n
5 2 0
Solution NR2
What radioactive isotope is produced
in the following bombardment of
boron?
10B + 4He 13N + 1n
5 2 7 0
nitrogen
radioisotope
Day 2 – Radioactivity Effects
and Applications
Detecting Radioactivity
To detect something, you need to
identify something it does
radioactive rays cause air to
become ionized
Detection (continued)
Geiger-Müller Counter works by
counting electrons generated when
Ar gas atoms are ionized by
radioactive rays
Detecting Radioactivity
(continued)
radioactive rays cause certain
chemicals to give off a flash of
light when they strike the
chemical
a scintillation counter is able to
count the number of flashes per
minute
Scintillation Counters
The Key Components of a Typical Scintillation Counter
Na(Tl)I
crystal
X- or Photo-
rays cathode
High voltage
supplier and
multi-channel
analyzer /
computer
system
Thin Al Photomultiply tube
window
Photons cause the emission of a
short flash in the Na(Tl)I crystal.
The flashes cause the photo-cathode
to emit electrons.
Scintillation
Detector
Detecting Radioactivity
(continued)
radioactive rays cause chemical
changes in some materials
Photographic film is able to
“record” its interactions with
radioactive particles
Photographic Emulsions and
Films
Sensitized silver bromide grains of emulsion develope
into blackened grains. Plates and films are 2-D
detectors.
Roentegen used photographic plates to record X-ray image.
Photographic plates helped Beckerel to discover radioactivity.
Films are routinely used to record X-ray images in medicine but
lately digital images are replacing films.
Stacks of films record 3-dimensional tracks of particles.
Photographic plates and films are routinely used to record
images made by electrons.
Half-Life
Not all radionuclides in a sample
decay at once (random process)
The length of time it takes one-half
the radionuclides to decay is called
the half-life
Half-life (continued)
Even though the number of
radionuclides changes, the length
of time it takes for half of them to
decay does not
the half-life of a radionuclide is
constant
Half-life (continued)
Each radionuclide has its own,
unique half-life
The radionuclide with the shortest
half-life will have the greater number
of decays per minute (For samples
of equal numbers of radioactive
atoms)
Half-Life of a Radioisotope
The time for the radiation level to fall
(decay) to one-half its initial value
decay curve
initial
1
half-life
2 3
8 mg 4 mg 2 mg 1 mg
Examples of Half-Life
Isotope Half life
C-15 2.4 sec
Ra-224 3.6 days
Ra-223 12 days
I-125 60 days
C-14 5700 years
U-235 710 000 000 years
Learning Check NR3
The half life of I-123 is 13 hr. How
much of a 64 mg sample of I-123 is left
after 26 hours?
Solution NR3
t1/2 = 13 hrs
26 hours = 2 x t1/2
Amount initial = 64mg
Amount remaining = 64 mg x ½ x ½
= 16 mg
Ionizing Radiation
radioactivity measurements
High energy particles and photons that ionise atoms and molecules
along their tracks in a medium are called ionizing radiation. For
example, , , , cosmic rays and X-rays are ionizing radiation.
Most radioactive measurement are based on their ionizing effect.
Ionizing radiation causes illness such as cancer and death.
Radiation effect is a health and safety concern.
Ionizing radiation can also be used in industry for various purposes.
Light and microwaves that do not ionize atoms and molecules are
called non-ionizing radiation.
Interaction of Heavy Charged Particles with
Matter
Sketch of Alpha Particle Paths in a Medium
Fast moving protons, 4He,
and other nuclei are
heavy charged particles.
source
Coulomb force dominates
charge interaction. Shield
They ionize and excite
(give energy to) molecules
on their path.
Scattering of Electrons in a Medium
An Imaginary Path of a particle in
a Medium
Fast moving electrons are
light charged particles.
They travel at higher speed.,
but scattered easily by
electrons.
source
Shield
Factors that Determine
Biological Effects of Radiation
The more energy the radiation has
the larger its effect can be
The better the ionizing radiation
penetrates human tissue, the deeper
effect it can have
Gamma >> Beta > Alpha
Factors that Determine
Biological Effects of Radiation
(continued)
Factors that Determine
Biological Effects of Radiation (continued)
The more ionizing the radiation
(based on mass and charge), the
greater effect the radiation has
Alpha > Beta > Gamma
Radiation Protection
Shielding
alpha – paper, clothing
beta – lab coat, gloves
gamma- lead, thick concrete
Limit time exposed
Keep distance from source
Factors that Determine
Biological Effects of Radiation
(continued)
Factors that Determine
Biological Effects of Radiation (continued)
The radioactive half-life of the
radionuclide
° The biological half-life of the element
±The physical state of the radioactive
material
Factors that Determine
Biological Effects of Radiation (continued)
The amount of danger to humans of
radiation is measured in the unit
rems
Somatic Damage
Somatic Damage is damage which
has an impact on the organism
Sickness or Death
May be seen immediately or in the
future
Depends on the amount of
exposure
Future effects include cancer
Genetic Damage
Genetic Damage occurs when the
radiation causes damage to
reproductive cells or organs
resulting in damage to future
offspring
Nuclear Technologies
X-rays give penetrating vision to inner structures under cover.
X-rays and computers give 4-D images of wholes.
X-ray diffraction enables us to determine crystal and molecular
structures, including those of DNA.
Ionizing radiation effects and sterilization empower industries.
Radioactive decay kinetics enables dating.
Radioactivity causes and cures illness.
Nuclear reactions led to nuclide and element synthesis.
Pair productions give positrons and electrons for accelerators.
Positron-electron annihilations tell stories of organ functions.
Nuclear reactions activate atoms and nuclides in microscopic samples.
Fission and fusion energy for war and peace.
Radiology
Radiology is a scientific discipline dealing with medical imaging using
ionizing radiation, radionuclides, nuclear magnetic resonance, and
ultrasound. The following procedures are currently widely available:
Central Nervous System: Brain,Spine
Cardiovascular System: heart, blood vessels
Musculoskeletal System: bone, muscles, and joints
Digestive, Urinary, and Respiratory System: intestines,
kidneys, liver, stomach, lungs
Reproductive System and Mammography: male and
female reproductive organs and breasts
X-ray Tubes
-X-ray tubes for industry and
sciences.
- Non-destructive testing X-ray
Inspection and X-ray Baggage
Inspection and Thickness
Gauging.
--There are hundreds of X-ray
tubes for medical applications.
Image from prd004-5 of Varian.
X-ray Imaging
Absorption of X-ray and gamma-ray by different
material for image: today, 2-dimensional solid state
detectors are used in place of films for X-ray and
gamma-ray imaging as shown in this image by Varian
Mammography and CT Scan
X-rays provide the sharpest images of the breast's inner structure.
Mammogram detects small tumors and changes in the breast tissues.
Computed tomography (CT), scanner takes images by rotating an x-
ray tube around the body while measuring the constantly changing
absorption of the x-ray beam by different tissues in your body.
The sensitive scanner provides small
differences in absorption of the beam by
various tissues. The information is fed into
a computer which reconstruct images of
thin cross sections of the body.
Impact of X-ray Diffraction
Using X-ray diffraction, nearly all structure
of compounds artificially made or isolated
from nature have been determined,
including structures of semiconductors,
DNA molecules, and proteins. Structure
data banks serve science, technologies,
and medicine.
X-ray Diffraction Results
X-ray diffraction pattern of a single crystal
showing positive image of X-ray beams.
Intensities of these beams allows us to
determine molecular and crystal structures.
Various data banks of structures are now
available for research and development.
Medical Uses of Radioisotopes,
Diagnosis
Diagnosis (radiotracers)
Usually gamma emitters
Little interaction with tissue
Therapy
Alpha or beta emitters (interact with tissue)
May also emit gamma (detect outside body)
Medical Uses of Radioisotopes,
Diagnosis
radiotracers
certain organs absorb most or all of a
particular element
can measure the amount absorbed by
using tagged isotopes of the element
and a Geiger counter
Radionuclide in Medicine
Radionuclides are used in imaging for diagnosis and treatment.
Nuclides specifically accumulate in organs (based on chemical
properties) for image and diagnoses.
Radionuclide therapy selectively deliver radiation doses in
target tissues.
History of Nuclear Midicine
1895 – discovery of X-rays
1934 – discovery of artificial radioactivity
1937 – artificial radioactivity was used to treat leukemia at UC Berkeley
1946 – use of radioactive iodine cured thyroid cancer
1948 – Abbott Laboratories began distribution of radioistopes
1950s – radioactive iodine was widely used to diagnose and treat thyroid
1953 – Gordon Brownell and H.H. Sweet built a positron detector
1971 - The American Medical Association officially recognized nuclear
medicine as a medical speciality
About Nuclear Medicine
There are nearly 100 different nuclear medicine imaging
procedures available today.
Nuclear medicine uniquely provides information about
both the function and structure of virtually every major
organ system within the body.
There are approximately 2,700 full-time equivalent nuclear
medicine physicians and 14,000 certified nuclear medicine
technologists in the U.S.
Nuclear Medicine
Applications
Neurologic: Diagnose stroke, alzheimer’s disease, localize seizure foci, evaluate
post concussion
Oncologic: Tumor localization, staging, and response to treatments
Orthopedic: Evaluate bone, arthritic changes, and extent of tumors
Renal: Detect urinary tract obstruction and measure renal functions
Cardiac: Diagnose coronary artery, measure effectiveness of bypass surgery,
identify patients of high risk heart attack, and diagnose heart attacks
Pulmonary: Measure lung functions
Other: Diagnose and Treat Hyperthyroidism (Grave's Disease)
Irradiation Sterilization
Irradiation by ionizing radiation kills bacteria and cells. This effect
has been applied for the following areas:
sterilize medical equipment
sterilize consumer products such as baby bottle, pacifiers, hygiene
products, hair brush, sewage
sterilize common home and industry products
food preservation
Irradiation for Food
Processing
Soon after discovery, X-rays were used to kill insects and their eggs.
After WWII, spent fuel rod were used to sterilize food, but soon, 60Co
was found easier to use in th 1950s.
The US army played a key role in R & D of food processing, and
soon other countries followed.
In 1958, USSR granted irradiation of potatoes for sprout inhibition.
Canada granted irradiation of potatoes, onions, wheat, dry spices.
However, food processing has many other problems such as
regulation, labelling, marketing and public acceptance to deal with.
Object dating
archeological (once living materials)
compare the amount of C-14 to C-12
C-14 radioactive with half-life = 5730yrs.
while living, C-14/C-12 fairly constant
Object dating (continued)
CO2 in air ultimate source of all C in
body
atmospheric chemistry keeps
producing C-14 at the same rate it
decays
Upon death, C-14/C-12 ratio decreases
limit up to 50,000 years
Radiocarbon Formation
and Exchange
Cosmic
rays
n 14N proton
14C
14CO
2 CO2
Physical Data of 14C
Beta energy 156keV (maximum), 49 keV (ave)
Half life 5730 y
Biological half life 12 d
Effective half life 12 d (unbound)
40 d (bound)
Max. beta range in air 24 cm
Max. beta range in water 0.28 mm
Best used to date objects less than 50,000 years old.
Object Dating
mineral (geological)
compare the amount of U-238 to
Pb-206
compare amount of K-40 to Ar-
40
Radiopotassium 40K Dating
Radiopotassium 40K decays to stable 40Ar. Thus, by measuring relative
ratio of 40K and 40Ar in rocks enable us to determine the age of rocks
since its formation.The half life of 40K is 1.25e9 y.
Fissionable Material
fissionable isotopes include U-235, Pu-
239, and Pu-240
natural uranium is less than 1% U-235
rest mostly U-238
not enough U-235 to sustain chain
reaction
Fissionable Material
(continued)
fission produces about 2.1 x 1013
J/mol of U-235
26 million times the energy of
burning 1 mole CH4
to produce fissionable uranium the
natural uranium must be enriched in
U-235
Fission Chain Reaction
a chain reaction occurs when
a reactant is also a product
in the fission process it is the
neutrons
only need a small amount of
neutrons to keep the chain
going
Fission Chain Reaction
(continued)
many of the neutrons produced
in the fission are either ejected
from the uranium before they hit
another U-235 or are absorbed by
the surrounding U-238
Fission Chain Reaction
(continued)
minimum amount of fissionable
isotope needed to sustain the
chain reaction is called the
critical mass
Nuclear fission
Nuclear fission
Nuclear Power Plants
use fission of U-235 or Pu-240 to
make heat
the fission reaction takes place in
the reactor core
Nuclear Power Plants
Nuclear Power Plants
(continued)
heat picked up by coolant and
transferred to the boiler
in the boiler the heat boils water,
changes it to steam, which turns
a turbine, which generates
electricity
Nuclear Power Plants -
Core
the fissionable material is stored in
long tubes arranged in a matrix
called fuel rods
subcritical
Nuclear Power Plants -
Core (continued)
between the fuel rods are
control rods made of neutron
absorbing material
B and/or Cd
neutrons needed to sustain the
chain reaction
Nuclear Power Plants -
Core (continued)
the rods are placed in a material
used to slow down the ejected
neutrons called a moderator
allows chain reaction to occur
below critical mass
Reactor core (fuel):
enriched or natural U, 239Pu
Moderators
graphite,
H2O, D2O Key Components
He (100 Atm and 1273 K)
Be (high temperature liquid metal). of Nuclear
Na (773 to 873 K for breeder reactor)
BeF2 + ZrF4 ( for GCR) Reactors
Control rods
Cadmium, Boron, Carbon, Cobalt, Silver,
Hafnium, and Gadolinium, c =255 kb for 157Gd Monitoring devices
Neutron and radioactivity detectors, T, etc
Energy transfer system
Moderator or liquid
Reactor accidents
An accident is a series of undesirable events that took
place due to accumulated causes.
Nuclear accidents attract more attention due to release of
radioactive nuclides.
Radioactivity causes fear, because most people know
little about it.
Many nuclear accidents have happened.
TMI-2 Reactor accidents
March 28, 1979, two pumps failed to supply feed water
steam generator.
Valve of auxiliary pump was closed by error and auxiliary
pump failed to operate.
Pressure increased and relieve valves opened.
Relieve valves failed to close resulting in a loss of coolant.
Zircaloy-4 oxidized by water, producing a large volume of
hydrogen gas.
Core overheated resulting in meltdown
The TMI-2 Reactor Design
The TMI-2 Core After the Accident
Four years later,
photo image of
TMI–2 core shows
damage to its
uranium fuel rods
more extensive
than originally
thought just after he
accident.
Core meltdown
shows the
temperature
reached 5000 K.
http://washingtonpost.com/wp-srv/national/longterm/tmi/gallery/photo10.htm
Fission Products in the Core After the Accident
Long-life Fission Products in the Core after TMI-2 Accident
Isotope Activity /Ci Half-life Amount*
85K 9.7104 10.7 y 4.71013
90Sr 7.5105 28.8 y 9.81014
129I 2.210–3 1.6107 y 1.61012
131I 7.0107 8.04 d 7.01013
133Xe 1.5108 5.25 d 9.81013
137Cs 8.4105 30.2 y 1.11015
* Amount = Activity half-life (s)/0.693
The Chernobyl Accident
RBMK graphite-moderated, channel-tube-cooled reactors. Reactor 4
in Chernobyl had been in operation for 3 years prior to the accident.
April 26, 1986, Reactor 4 at Chernobyl was scheduled for a safety test
to see if residual power is sufficient to operate the reactor safely in
case of a sudden power failure.
Operators turned off cooling system and powered down. When power
from the reactor failed to operate the reactor safely, they used power
from the grid without notifying grid controller. Radioactivity of fission
products overheat the core. When they turned up power with cooling
system off, the core fragmented and exploded destroying the building.
Radioactivity (fallout) spread to north Europe.
The Soviet RBMK Reactor Design
The Soviet
RBMK reactor
has individual
fuel channels,
using ordinary
water as
coolant and
graphite as
moderator. It
evolved from
reactors
designed for
239Pu
production.
Power Nuclear Reactors in the World
nucleartourist.com/world/wwide1.htm
Major work sites:
The First Fission Oak Ridge 59,000-acre
Bomb Explosion Hanford Engineer Work 450,000-acre
Project Y (Los Alamos Laboratory)
Chicago, Berkley, Montreal, New York
July 16, 1945, a
plutonium (Fat Man)
bomb was tested in
Journey of Death. Two
hemispheres of 239Pu
were forced together to
reach criticality. The
bomb was attached to a
30-meter steel tower,
which disappeared after
the explosion.
Fission Energy For War
At 8:15 am August 6, 1945, Little Boy (235U) was dropped
on Hiroshima by a modified B-29 bomber.
On the 9th, a 239Pu-fuelled bomb exploded over Nagasaki
Destruction by atomic bomb
Light and energy (heat)
Shock wave
Secondary fire
Radioactive fission products
in the fallout
The Implosion Arrangement
Ignition Chemical
points explosive
Reducing
Critical 239
Pu
Masses by
Implosion
Fission material is surrounded by chemical explosive
which is ignited at many points simultaneously. The
explosion forces pieces of 239Pu together and even
reduces the volume to reduce the critical mass.
Producing Bomb Materials
Separate 235U (0.7%) from natural 235
U
uranium: 239
Pu
gas diffusion of UF6
centrifuge of UF6 gas
thermal diffusion of UF6 gas
electromagnetic separation
Production of 239Pu by the reaction
238U(n, 2)239Pu
Bomb Material: Separating 235U by gas Diffusion
One diffusion unit
and
the diffusion plant
The blue spot is a person
http://www.npp.hu/uran/3diff-e.htm
Bomb Material: SSeparating235U by Electromagnetic method
Bomb Material: eparating 235U by Electromagnetic meth
Uranium Isotope Enrichment by the
Electromagnetic Method. The principle of this
method is the same
as the mass
spectrometry for
chemical analysis.
This is still a very
important method for
chemical analysis
today.
From a 238
UF6
particle 235
UF6 collector
accelerator collector
Isotope Separation by
Plasma Centrifuge
A vacuum arc produces a plasma column which rotates by action of
an applied magnetic field. The heavier isotopes concentrate in the
outer edge of the plasma column resulting in an enriched mixture
that can be selectively extracted
Nuclear Fusion
Fusion is the process of
combining two light nuclei to
form a heavier nucleus
The sun’s energy comes from
fusion of hydrogen to produce
helium
Nuclear Fusion (continued)
Releases more energy per gram
than fission
Requires high temperatures and
large amounts of energy to
initiate, but should continue if you
can get it started
Nuclear Fusion
Fusion
small nuclei combine
2H + 3H 4He + 1n + Energy
1 1 2 0
Occurs in the sun and other stars
Nuclear Fusion in
Stars
Stars are giant fusion reactors.
Nuclear fusion reactions
provide energy in the Sun and
E = mc2 other stars. Solar energy
1H, 2D
drives the weather and makes
3T, 4He
plants grow.
Energy stored in plants
sustains animal lives, ours
included.
The Sun
Core:
Radius = 0.25 Rsun
T = 15 Million K
Density = 150 g/cc
Envelope:
Radius = Rsun = 700,000 km
T = 5800 K
Density = 10-7 g/cc
Life of Star:
tug-of-war between Gravity &
Pressure
The
solar
surface
Nuclear Fusion and Plasma
D and T mixtures have to be
heated to 10 million degrees. At
these temperatures, the mixture is Plasmas
a plasma.
A plasma is a macroscopically
neutral collection of charged
particles. Fires
Ions (bare nuclei) at high Stars
temperature have high kinetic
energy and they approach each
other within 1 fm, a distance Neon lights
strong force being effective to
cause fusion.
Nuclear Fusion and Plasma
Confinements
Three confinement methods
fd3.gif from ippex.pppl.gov/ippex/module_5/see_fsn.html
Nuclear Fusion using
Tokamak
The Tokamak
technology for
plasma
confinement in
fusion
fd4.gif<=ippex.pppl.gov/ippex/module_5/see_fsn.html
Fusion Research in U.S.A.
•Princeton Plasma Physics Laboratory (PPPL).
•Oak Ridge National Laboratory (ORNL).
•Massachusetts Institute of Technology, Alcator C-
Mod.
•University of Wisconsin, HSX.
•University of Texas, Fusion Research Center.
•Max Planck Institut fur Plasmaphysik, Wendelstein 7-
AS
Nuclear Fusion Energised the
Cold War
During WW2, the USSR competed with UK and US for military
superiority. The Cold War started.
Sept. 23, 1949, President Truman told the world about the Soviet
explosion of A-bomb.
The US stepped up to develop the H-bomb.
1952, Nov. 1. US tested the first H-bomb at Enewetak
1953 the USSR tested an H-bomb
Britain, France, and China also have tested H-bombs.
The cold war was red hot until the former USSR disintegrated.
H-bomb
Nov. 1, 1952, the first H-
bomb Mike tested,
mushroom cloud was 8 miles
across and 27 miles high;the
canopy was 100 miles wide,
80 million tons of earth was
vaporized.
H-bomb exploded Mar. 1,
1954 at Bikini Atoll yielded 15
megatons and had a fireball 4
miles in diameter.
USSR H-bomb yields 100
megatons.
Energy & Nuclear Science
The most important aspect of nuclear
technology is the large amount of
energy involved in nuclear changes,
radioactivity, nuclear reactions,
radiation effects etc.
Thus, the energy concept is very
important before we start to explore
nuclear science.
Nuclear energy associates with mass
according to Einstein’s formula, E = m c2
E=mc2
but what does it mean?
Where does the energy come
from?
At the nuclear level, mass and
energy are interchangeable.
Mass is converted to energy
Energy is converted to mass
Where does the energy come
from?
The mass of a nuclide is less
than the sum of the masses of its
constituent parts (protons and
neutrons
Where does the energy come
from?
Proton = 1.00728 amu
Neutron = 1.00866 amu
Expected mass of 4 He
2
2 x 1.00728 + 2 x 1.00866
=4.03188 amu
Where does the energy come
from?
Actual mass of 4
2 He
= 4.0026 amu
Difference = 0.02928 amu
Where did this mass go?
Where does the energy come
from?
The difference in the expected mass
and the actual mass is called the
“mass defect.”
This mass is converted into the
energy used to hold the nucleus
together.
Where does the energy come
from?
Protons are positively charged. If there
were no force holding them together,
the protons in the nucleus would repel
each other.
This force is called the nuclear strong
force.
The energy used for this force is called
“binding energy.”
Where does the energy come
from?
E = mc2
Binding energy = (mass defect) x c2
Note: mass defect must be in kg
(1 amu = 1.66054x10-27 kg)
Where does the energy come
from?
Binding energy for 4
2 He
0.02928amu(1.66054 x 10-27 kg/amu)
= 4.86206 x 10-29 kg
E = 4.86206 x 10-29 kg x (2.998x108 m/s)2
= 4.3700x10-12 J
Estimate Energy in Nuclear
Reactions
Similarly, the energy in a nuclear reaction is determined based on the
mass difference between the mass of the reactants and the mass of the
products.
Energy = (mass of products – mass of reactants) x c2
For exothermic reactions (e.g., fission or fusion) the mass of the
products is less than the mass of the reactants. In these reactions, the
mass is converted to energy.
Learning Check NR4
Indicate if each of the following are
(1)Fission (2) fusion
A. Nucleus splits Energy
B. Large amounts of energy released
C. Small nuclei form larger nuclei
D. Hydrogen nuclei react
Solution NR4
Indicate if each of the following are
(1)Fission (2) fusion
A. 1 Nucleus splits
B. 1 + 2 Large amounts of energy
released
C. 2 Small nuclei form larger nuclei
D. 2 Hydrogen nuclei react
